In the semiconductor industry, apparatus, such as chemical vapor deposition (CVD) apparatus, for forming films has been used to deposit various layers over the substrate. However, for larger wafer sizes, control over film profile becomes more difficult and CVD has issues of film profile uniformity, such as development of protrusions and/or depressions in the film. Control over spacing between a shower head and the substrate, the power supplies, or the flow of dilution gases has not provided satisfactory control.